Along an assembly line, various types of articles, such as diapers and other absorbent articles, may be assembled by adding components to and/or otherwise modifying an advancing, continuous web of material. In some processes, advancing webs of material are combined with other advancing webs of material. In other processes, individual components created from advancing webs of material are combined with advancing webs of material, which in turn, are then combined with other advancing webs of material. In some cases, individual components created from advancing web or webs are combined with other individual components created from other advancing web or webs. Webs of material and component parts used to manufacture diapers may include: backsheets, topsheets, leg cuffs, waist bands, absorbent core components, front and/or back ears, fastening components, and various types of elastic webs and components such as leg elastics, barrier leg cuff elastics, stretch side panels, and waist elastics. Once the desired component parts are assembled, the advancing web(s) and component parts are subjected to a final knife cut to separate the web(s) into discrete diapers or other absorbent articles.
In some converting configurations, discrete chassis spaced apart from each other are advanced in a machine direction and are arranged with a longitudinal axis parallel with the cross direction. Opposing waist regions of discrete chassis are then connected with continuous lengths of elastically extendable front and back belt webs advancing in the machine direction. While connected with the chassis, the front and back belt webs are maintained in a fully stretched condition along the machine direction, forming a continuous length of absorbent articles. The continuous length of absorbent articles may then be folded in a cross direction. During the folding process in some converting configurations, one of the front and back belt webs is folded into a facing relationship with the opposing belt. The front and back belts may then be bonded together to create the side seams on diapers.
Portions of the front and back belt may be partially melted and compressed together to create side seams. The seaming process may include advancing the front and back belts through a nip formed between a rotating anvil roll and a rotating compression tool. As the front and back belts advance through the nip, the compression tool may compress the front and back belts against the anvil roll. The anvil and the compression tool may be made of a rigid material. In some processes, the amount of time that the front and back belts are compressed may affect the strength and quality of the seam. In particular, increased compression time may increase the quality and strength of the seam. However, in a high speed manufacturing process utilizing a rigid anvil roll and a rigid compression tool, the anvil roll and the compression tool may be spaced apart so as to prevent interference between the anvil roll and the compression tool. As a result, the compression time may be nearly instantaneous as the front and back belts pass through the nip formed between the anvil roll and the compression tool.
In some processes, compressing the advancing substrates in a direction that is non-tangential to both the outer surface of the compression tool and the outer circumferential surface of the anvil roll may improve the seam quality and strength. However, in a process utilizing a rigid compression tool and a rigid anvil roll spaced apart so as to prevent interference, the substrate may be compressed in a direction that is tangential to both the outer surface of the anvil roll and of the compression tool.
Thus, it would be beneficial to provide an apparatus and a method for increasing the compression time for bonding substrates together to form a side seam in a high speed manufacturing process. In addition, it would be beneficial to provide a process and apparatus for compressing substrates in a direction that is non-tangential to the outer surface of the compression tool and the outer circumferential surface of the anvil.